Have you ever wondered how it is that we recognise someone as a loved one? The poets would absolutely say something like ‘my heart recognises them’, but when we really think about it, it all comes down to seeing them and feeling some way about them; our brain adds a mix of perception, memory and emotion to the equation. When you look at your family or friends, you recognise their face, their voice, their small mannerisms and everything.
In a surprising twist documented in medical literature, a 73-year-old man with Parkinson’s disease developed Capgras Syndrome, where the person believes that a close one has been replaced by an imposter. Despite having lost his sight, he was utterly convinced that several impostors were replacing his wife. He didn’t need his sight to reach this conclusion; he claimed that he could spot the impostors purely by the sound of their voice or their clothes (Hermanowicz, 2002).
This calls for a question: exactly which part of his brain shows a lack when he all but claims that his wife is replaced? Is it his perception, or his memory, or his emotions?
From The Archives: The Case of Madame M
The condition was named after French psychiatrist Joseph Capgras, who first described it way back in 1923, when he, alongside his intern Jean Reboul-Lachaux, treated a woman known in the medical archives as Madame M (Capgras & Reboul-Lachaux, 1994). Madame M. had a complex web of delusions (Sinkman, 2008). She believed that her children, her husband, her neighbours, and even the local police had been replaced by identical look-alikes or “doubles.”
For decades, early theorists explained Capgras syndrome through a psychoanalytic lens, arguing that unresolved feelings of love or hostility toward a family member drove the condition. To cope with this internal guilt, the patient’s mind supposedly creates an imposter to serve as a safe target for the negative emotions (Berson, 1983).
However, in the late 20th century, as brain-imaging technology advanced, scientists found that Capgras was less about hidden Freudian guilt and far more about structural and functional issues in the brain. With all the information accessible and understood as of now, Capgras often emerges alongside neurological conditions (non-psychiatric) like Alzheimer’s disease, Lewy body dementia, traumatic brain injuries, and occasionally psychiatric conditions like schizophrenia (Bell et al., 2017; Fiacconi et al., 2014; Posa et al., 2025).
Read More: Capgras Syndrome: The Delusion of Doppelganger
What Neuroscience Says About Capgras Syndrome
To understand exactly how a loved one becomes a stranger, it is important to understand how a ‘healthy’ brain recognises a face. Neuroscience explains that the brain processes faces using a dual-route, meaning it splits the ‘job’ across two separate pathways running simultaneously (Bruce & Young, 1986; Ellis & Lewis, 2001).
1. The Cognitive Route
This pathway is purely analytical; it maps out facial features and cross-references them against our memory. While this may seem like it’s a long process of looking at a face, recognising some facial features, then comparing them with the features memorised, and then coming to a conclusion, it’s all a split-second process really. People look at the face and immediately conclude, “Oh! That’s my mother.”
2. The Affective Route
This pathway connects deeply with our brain’s emotional switchboard, the amygdala (Posa et al., 2025). This route generates an immediate response of familiarity that recognises if the person matters. Think of it as if the brain is extending a sense of safety and security towards this person because there is a familiarity attached to them.
In Capgras syndrome, the thinking part of the route is working fine, but the emotional part is damaged (Ellis & Young, 1990; Poole & Wilkinson, 2024). When someone with Capgras syndrome looks at their partner, their brain correctly recognises their face, but they don’t feel the warmth they expect. This leads to an upsetting situation called sensory-affective dissonance (Hermanowicz, 2002). The brain is left with a jarring question: If this truly is my partner, why do I feel absolutely nothing when I look at them?
To resolve this contradiction, the brain reasons a narrative that might bridge a gap and lands on the only possible explanation that my person has been replaced by another who only shares their physical appearance.
Is Capgras Syndrome Merely a Defect in Brain Functions?
Capgras syndrome, while it has shown defects in brain functioning, is still considered a delusion of doubles, a part of delusional misidentification syndrome. Since the first documented case of Capgras syndrome, professionals have emphasised that the ‘narrative’ that the brain creates develops into a false belief. If broken emotional wiring were the only problem, anyone experiencing an emotional disconnect would develop Capgras (Shah et al., 2023). It is important to understand that Capgras syndrome is equal parts brain defect as well as a symptom of psychosis. Psychiatric and non-psychiatric conditions can both involve Capgras syndrome (Shah et al., 2023).
Neuropsychologists like Coltheart have demonstrated that full-blown delusions require a two-step failure (Coltheart et al., 2007; Davies et al., 2001). Our brain has, among many other functions, a reality checker of sorts that either accepts or denies bizarre theories. In Capgras patients, damage (in non-psychiatric patients) or underactivity (in psychiatric patients) in this function leads to acceptance and sustenance of the narrative (Devinsky, 2009; Fiacconi et al., 2014).
Our Body Recognises Familiarity
Our body has a way to recognise a familiar face; skin conductance response (SCR) tracks the tiny changes in sweat gland activity caused by emotions. In an astonishing study, it was found that if a healthy person is shown a picture of a random stranger vs. a photo of their own parents, their body triggers a spike in skin conductance for the parent. However, when tested for Capgras patients, they found that their body reacted to a loved one’s photo with the same indifferent, flat response as they would to a total stranger (Ellis et al., 1997; Poole & Wilkinson, 2024).
Conclusion
Humans live this life and search for safety in the people around them, in the space they create with them. Imagine the fear of the person with the syndrome: that person before them is not the one they love, but someone totally strange, an imposter; imagine living with this knowledge that they are not safe. Now imagine how the said imposter must feel when their loved one does not recognise them; imagine the devastation felt that their loved one can no longer love them or be loved by them. The best takeaway from this could be the knowledge that emotions are an anchor for us. Without them, we lose our humanity, and then, in some cases, we are met with familiar strangers.
References +
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